Tensile properties of all-polymeric syntactic foam composites: Experimental characterization and mathematical modelling

All-polymer syntactic foams are studied under large strain cyclic and monotonic tensile loading in order to reveal their stress-strain behaviour, recoverability, strength, elongation at break. The foam study here consists of hollow thermoplastic microspheres (HTMs) two distinct grades (551 920), with distributions mean-wall thicknesses diameters, embedded inside a polyurethane matrix various volume fractions. Cyclic loading-unloading curves recorded, revealing the level viscoelasticity exhibited by materials (which becomes stronger effect increasing fractions HTMs) indicating repeatability strain. Samples also subjected Higher HTMs increase stiffness material whilst it is observed that highly elastic over wide range strains, damage arises lower levels for more filled materials. HTM thus exhibit breaking strains compared neat matrix, which attributed matrix-microsphere interfacial debonding. Furthermore, employing optimization techniques, linear properties an average shell thickness 551 grade inferred comparing experimental results predictions from Generalized Self-Consistent Method, incorporating polydispersity data on size distribution microspheres. These complement previous work involved direct measurements 920 thickness. Results indicate characterization microsphere not critically dependent access high resolution diameter data, provided accurate representative mean known. Finally, thermal degradation samples using thermogravimetric analysis (TGA) reveals can be added without significantly affecting stability material.